The present disclosure relates to a fuel supplier for an automobile, which has a fuel pump for pumping fuel from a fuel tank to an internal combustion engine, a motor for driving the fuel pump and a control unit. The control unit carries out feedback control of the duty ratio of the electric voltage applied to the motor such that the fuel pressure comes close to the target fuel pressure.
Japanese Laid-Open Patent Publication No. 2008-121563 discloses a common fuel supplier for an automobile. With respect to this fuel supplier, a target fuel pressure may be determined based on the engine load detected by signals from various sensors. Feedback control is then carried out such that actual fuel pressure is equal to the target fuel pressure.
In the situation where the actual fuel pressure is controlled to be equal to the target fuel pressure by feedback control, the motor is regulated such that the number of revolutions of the fuel pump becomes the requisite minimum number. This may occur, for example, when the accelerator is not pressed. In this condition, the actual fuel pressure is substantially equal to the target fuel pressure during an idling condition of the engine
As shown in FIG. 13A, when the accelerator is pressed in order to drastically increase an open ratio, a throttle valve is opened, and the amount of intake air supplied to the internal combustion engine increases. When the amount of the intake air increases, the fuel amount injected into the engine increases. Therefore, as shown in FIG. 13B, the number of revolutions of the engine increases.
At this time, because the number of revolutions of the fuel pump is held at the requisite minimum by feedback control, the amount of supplied fuel is less than the amount of fuel consumption of the engine, and the fuel pressure decreases below the target fuel pressure. When deviation between the actual fuel pressure and the target fuel pressure is generated, a motor is controlled such that the number of revolutions of the fuel pump increases based on the deviation. Accordingly, the amount of fuel supplied to the engine increases.
During feedback control, the actual fuel pressure decreases below the target fuel pressure, the deviation generates, and then control is carried out in order to increase the umber of revolutions of the fuel pump. Thus, there is a time delay (TD) between pressing the accelerator and the increase in the number of revolutions of the engine. Accordingly, there has been a need for improved fuel suppliers.